IN LIVING MATTER 13 



upon the matter here than to indicate that, in the kidney, for 

 example, urea solution is concentrated from less than '04 per cent, 

 in the circulating blood up to 2 per cent, in the urine, and that 

 in this process no matter what may be the intermediate stages, 

 the kidney cells develop volume energy, against the usual laws 

 applicable to inert semi-permeable membranes, just as much as a 

 mechanical engine attached to a piston and cylinder would do 

 in compressing a gas from a pressure of about 130 mm. of 

 mercury and a volume of 75,000 c.c. to a pressure of about 

 6500 mm. of mercury and a volume of 1500 c.c., these being the 

 volumes of the blood and urine and pressures of the '04 and 2 per 

 cent, solutions respectively. 



In the face of this experimental evidence, surely it is time to 

 cease regarding kidney cells as semi -permeable membranes to 

 which the laws of osmosis apply. The case is exactly the reverse 

 of the semi -permeable membrane, in which the solvent passes 

 through, tending to equalise pressures and reduce volume energy ; 

 for in the kidney cell the dissolved substance passes through at 

 a greater rate than the solvent, increasing the difference in 

 pressure on the two sides and developing volume energy. 



It is not intended at all to represent that the phenomena 

 described are contrary to the laws of energetics, but to make 

 clear that the cell does not play the part of an inert membrane, 

 that the laws of osmosis deduced from observations on inert 

 membranes do not apply, and that there is a form of energy and 

 type of energy-transformer at work which are not to be observed 

 elsewhere than in living cells. 



The study of the properties of this particular energy-trans- 

 former, and the interactions between biotic energy and the in- 

 organic forms of energy carried out by its action, is the province 

 of the biologist, who must approach and has been approaching 

 the subject in the same manner as the physicist and chemist 

 approach the study of other types of energy that is, by acting 

 upon the cell with other types of energy, and studying its reaction 

 to such treatment. 



Experiments on any form of energy consist in observing the 

 interactions between it and other forms, in studying the nature 

 of the transformer, and of the changes, if any, which occur 

 in it. 



The structure of the cell must hence be taken up from the 



